We introduce a NO_ROLLBACK flag for InnoDB tables. This flag only works
for tables that have a single index. Apart from undo logging, this flag
will also prevent locking and the assignment of DB_ROW_ID or DB_TRX_ID,
and imply READ UNCOMMITTED isolation. It is assumed that the SQL layer
is guaranteeing mutual exclusion.

After the initial insert of the single record during CREATE SEQUENCE,
InnoDB will be updating the single record in-place. This is crash-safe
thanks to the redo log. (That is, after a crash after CREATE SEQUENCE
was committed, the effect of sequence operations will be observable
fully or not at all.)

When it comes to the durability of the updates of SEQUENCE in
InnoDB, there is a clear analogy to MDEV-6076 Persistent AUTO_INCREMENT.
The updates would be made persistent by the InnoDB redo log flush
at transaction commit or rollback (or XA PREPARE), provided that
innodb_log_flush_at_trx_commit=1.

Similar to AUTO_INCREMENT, it is possible that the update of a SEQUENCE
in a middle of transaction becomes durable before the COMMIT/ROLLBACK of
the transaction, in case the InnoDB redo log is being flushed as a result
of the a commit or rollback of some other transaction, or as a result of
a redo log checkpoint that can be initiated at any time by operations that
are writing redo log.

dict_table_t::no_rollback(): Check if the table does not support rollback.

BTR_NO_ROLLBACK: Logging and locking flags for no_rollback() tables.

DICT_TF_BITS: Add the NO_ROLLBACK flag.

row_ins_step(): Assign 0 to DB_ROW_ID and DB_TRX_ID, and skip
any locking for no-rollback tables. There will be only a single row
in no-rollback tables (or there must be a proper PRIMARY KEY).

row_search_mvcc(): Execute the READ UNCOMMITTED code path for
no-rollback tables.

ha_innobase::external_lock(), ha_innobase::store_lock():
Block CREATE/DROP SEQUENCE in innodb_read_only mode.
This probably has no effect for CREATE SEQUENCE, because already
ha_innobase::create() should have been called (and refused)
before external_lock() or store_lock() is called.

ha_innobase::store_lock(): For CREATE SEQUENCE, do not acquire any
InnoDB locks, even though TL_WRITE is being requested. (This is just
a performance optimization.)

innobase_copy_frm_flags_from_create_info(), row_drop_table_for_mysql():
Disable persistent statistics for no_rollback tables.